What happens in your garden after you have picked the last of the summer tomatoes? Many of us plan only one growing season and concentrate on the heat-loving edibles such as tomatoes, peppers and eggplant. The rest of the year our gardens are sleeping, just waiting for the next summer season. But fall and spring plantings can make more efficient use of our garden space, and expand the variety of homegrown edibles we can enjoy.
Planting seasonally requires some knowledge of the soil and air temperature that crops require to reach maturity. Although it is common to classify edibles as cool or warm season crops, planting dates are not absolute. A number of conditions such as microclimates, size and type of planting beds, and sun exposure affect the soil and air temperature. A cool season crop such as spinach, which grows best in temperatures from 55 to 75 degrees, could be planted in February in a sunny Novato garden but might need to wait until March in Mill Valley. Choosing specific varieties geared to cooler weather also helps insure more reliable results. Warm season crops grow best when temperatures are 65 to 92 degrees. That’s why tomatoes grow faster after the soil warms up in May.
Another consideration in seasonal planting is crop rotation. This is an old farming practice that is important in keeping the soil healthy and reducing the risk of disease. Ideally, plants should be rotated each season through different areas of the garden according to family type. Micronutrient needs and pathogen susceptibility vary among the families, so rotation reduces soil depletion and discourages pests. Eggplant, peppers, potatoes and tomatoes are members of the Solanaceae family; while cucumbers, squash and melons belong to the Cucurbitaceae family; and cabbage, cauliflower and kale are Brassicaceae family members. A seasonal rotation plan among those families, for example, could designate one area of the garden for potatoes in the fall, kale in the spring and cucumbers in the summer.
When rotation is difficult, as in a small garden with limited sun exposure, maintaining soil fertility by adding compost and organic amendments is particularly important. Tomatoes, for example, are heavy feeders and will use up many of the nutrients in the soil each season.
If this all seems a bit too complicated, there are plenty of resources to help. The UC Marin Master Gardener website at marinmg.ucanr.edu has a “Great Gardening Information” link on the main page, which has links to “Tips on Growing Edibles” and the planting guide “Backyard to Belly.” The book “Golden Gate Gardening” by Pam Pierce is also an excellent source of published information on year-round gardening. Best of all, UC Marin master gardeners maintain an edible demonstration garden at Indian Valley organic farm and garden on the College of Marin campus in Novato, where you can see seasonal plantings and crop rotation in practice.
The Indian Valley farm was developed as a public educational garden to teach science-based horticultural practices for growing food at home. A variety of garden types are showcased, including different constructions of raised beds, straw bales, containers and edible landscaping. Techniques for maximizing space through easily constructed trellises and companion plantings can also be viewed. Produce grown in the garden meets Marin Organic Certified Agriculture standards and is sold by the farm. The garden can be visited anytime from 9 a.m. to 4 p.m. Monday through Saturdays. Edible gardening workshops are offered to the public on site. More information about gardening workshops and the edible demonstration garden can also be found on the UC Marin master gardener website.
Take advantage of Marin’s exceptional climate and the abundance of learning resources and experience the pleasure of a continuously productive garden. Don’t let your garden go to sleep this fall. With a bit of planning, you can enjoy fresh garden produce all year.